1. Field of the Invention
The invention relates to apparatus for nerve and/or muscle stimulation or cranial electrotherapy stimulation (CES). More specifically, the invention relates to such an apparatus which includes a programmable microprocessor for effecting control of the apparatus and for generating waveforms used in the operation of the apparatus. Even more specifically, the invention relates to such a stimulation apparatus which includes a novel electrode driver and monitor means.
2. Description of Prior Art
Apparatus of the general class of nerve and/or muscle stimulation are known in the art as illustrated, for example, in U.S. Pat. No. 3,902,502, Liss et al, Sept. 2, 1975, U.S. Pat. No. 4,084,595, Miller, Apr. 18, 1978, U.S. Pat. No. 4,121,594, Miller et al, Oct. 24, 1978, U.S. Pat. No. 4,147,171, Green et al, Apr. 3, 1979 and U.S. Pat. No. 4,148,321, Wyss et al, Apr. 10, 1979. From these patents, it is known to use a low frequency waveform modulated by a high frequency waveform. The high frequency waveform "breaks" the skin barrier, that is, it is able to penetrate through the capacitive effect of the skin as the capacitive effect of the skin presents a low impedance to a high frequency. The capacitive effect of the skin acts as a filter to the high frequency so that the nerves and/or muscles are stimulated only by the low frequency waveform. It is also known that a current pulse train should be used rather than a voltage pulse train, and, for example, the U.S. Pat. No. 3,902,502 teaches a source of constant current 20 for driving the electrodes. However, none of the patents teach an electrode driver of the same form and construction as per the present application.
Further examples of teachings in the art relating to the general class of nerve and/or muscle stimulation are given in U.S. Pat. No. 4,338,945, Hosugi et al, July 13, 1982, U.S. Pat. No. 4,088,141, Niemi, May 9, 1978, U.S. Pat. No. 4,398,537, Holmbo, Aug. 16, 1983, Canadian Pat. No. 1,175,493, Hepp et al, Oct. 2, 1984, Canadian Pat. No. 1,118,051, Keller Jr., Feb. 9, 1982, and Canadian Pat. No. 1,116,701, Hogfors et al, Jan. 19, 1982.
The U.S. Pat. No. 4,338,945 teaches a system for generating a randomized pulse train. The U.S. Pat. No. 4,088,141 teaches a system which is automatically disabled when a fault is detected. However, the detector and disabling are not similar to the teachings of the present application. The U.S. Pat. No. 4,398,537 is of interest in that it relates to an implanted nerve stimulator.
The Canadian Pat. No. 1,175,493 teaches a microprocessor based nerve stimulator. The Canadian Pat. No. 1,118,051 provides scanned output parameters, and the Canadian Pat. No. 1,116,701 teaches a stimulator with output signal controls.
None of the above references teach a stimulator wherein it is possible to apply a predetermined number of pulses, including a single pulse, by triggering the pulse train by an incoming trigger signal to the microprocessor.